PERFORMANCE AND MECHANISMS OF HINDERED AMINE LIGHT STABILIZERS IN POLYMER PHOTOSTABILIZATION

Abstract

Hindered amine light stabilizers (HALS) have probably been the most studied compounds in the field of polymer stabilization overthe past 15 years [1–16]. Their excellent performance in polyolefins [1–8], poly(vinyl chloride) [9], polystyrene [10], rubbers [11], polyamides [12], and other polymers such as acrylic resins 113–161 has made them an attractive item for research. There have been many advances regarding the understanding of the nature of the stabilization mechanism of these compounds, and there is still a great amount of controversy particularly with regard to the relative importance of some reactive intermediates [1–16]. This continuing research has led to the development of some novel compounds which are more efficient and have better compatibility with the polymer [1–16]. This article reviews the current understanding of the mechanism of action of HALS, its relationship with their performance in polymers, and their interaction with other additives used in a given stabilization system. The excellent performance of HALS in polyolefins has given rise to a great number of publications on their action in these polymers, and therefore most of the discussion will be related to this.